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A318987 Number of semigroups of order n without identity. 0
1, 0, 3, 17, 153, 1687, 26397, 1596113, 3682361420 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..8.

Index entries for sequences related to semigroups

FORMULA

a(n) = A027851(n) - A058129(n).

CROSSREFS

Cf. A027851, A058129.

Sequence in context: A145081 A020562 A193161 * A353258 A208832 A135751

Adjacent sequences:  A318984 A318985 A318986 * A318988 A318989 A318990

KEYWORD

nonn,more

AUTHOR

Steve Szabo, Sep 06 2018

EXTENSIONS

More terms from Joerg Arndt, Dec 09 2018

a(0) prepended by Jianing Song, Oct 26 2019

STATUS

approved

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Last modified May 26 12:47 EDT 2022. Contains 354091 sequences. (Running on oeis4.)